Growing Corn: How and When to Plant Corn, Step by Step

Successful corn yields depend on a number of factors, including seed choice, soil temperature, and moisture levels, planting timing, seeding depth, crop row spacing, and nutrient management. Understanding and accounting for these factors, along with proper disease and pest protection protocols, can have a large influence on your overall yield and profitability.

📸:@Hirurg via Canva/Featuring a grower inspecting corn. 

How to choose the appropriate seed variety when planting field corn 

Cost and yield aren't the only factors to consider when choosing seed for corn hybrids. It is also important to research the seed's early-season vigor, emergence rate, susceptibility to greensnap, grain drydown, disease tolerance, herbicide tolerance, and transgenic traits that protect the plant against insects.  

Obtaining reliable information on hybrid performance year over year and across multiple locations while identifying commonalities between trial conditions and your own fields is key. 

Based on productivity concerning field conditions, farmers sometimes speak in terms of two broad categories of corn hybrids: racehorses and workhorses. "Racehorses" are hybrids that consistently produce above-average yields in good conditions but below-average yield in poor conditions. On the other hand, "workhorses" typically produce consistent yields in good or bad conditions. Understanding which fields have the best and worst soil conditions can help you decide which variety will perform best in which location for maximum overall yield.¹  

Selecting a hybrid with an appropriate maturity rating is also vital. While high-yielding, later-maturing hybrids may seem appealing, your crops may potentially suffer if fields are not well drained and do not have sufficient load-bearing capacities for harvesting in the bad conditions that may occur in certain locations during late-season harvests.² Not all geographies have to contend with late-season storm threats, but understanding your location’s specific risks is key. 

When to plant corn 

Corn yield losses stem from a variety of factors, including short growing seasons, diseases, pests, inclement weather conditions, and delayed planting. Though the final yield is determined by the combination of yield-influencing factors that occur during the growing season, planting time shouldn’t be overlooked. 

The planting window for corn varies from state to state. For example, the optimal time to plant corn in Ohio is April 15 to May 10;³ in Iowa, it ranges from April 11 to May 9,⁴ and the recommended corn planting time for Indiana is April 20 to May 10.⁵  

State to state, the difference in the recommended time to start planting corn is typically greater than the difference in the end dates for planting season due to the shared concern for late planting penalties.  

Generally, you can expect a yield potential loss of one to two bushels per day for late-planted corn. Research from across the Midwest found that historically, the yield potential of corn planted from May 19 to 20 was 94 to 99% of corn planted by May 5 to 7.⁶ 

📸:@Hirurg via Canva/Featuring a grower assessing a field for planting corn. 

How do you assess a field for planting corn? 

Soil conditions are the most important indicator of when to plant corn. Understanding soil temperature, moisture, and how those variables affect the rate of corn germination, emergence, and development can help you plan a successful planting schedule.  

Best soil temperature and Growing Degree Days for planting field corn 

A healthy debate exists around what truly constitutes the lowest temperature at which you can safely plant corn. The general consensus is that at least 50 F is optimal (although some sources believe as low as 41 F is considered "safe").⁷ 

However, research indicates that the most accurate way to plan your planting schedule is to factor in how many Growing Degree Days (GDDs) are required for corn to germinate and emerge. GDDs are established based on the accumulation of heat units (HU) beginning the day after your specified planting date and are a way to quantify how the accumulation of HUs correlates to corn development milestones.  

An average of 115 GDDs is usually required for corn to emerge after planting, meaning if you expect corn to emerge in 10 days post planting, you will need to accumulate 11 to 12 GDDs per day in the period between planting and emergence. This would require approximately 10 days of 61 F to 62 F average soil temperatures per day.⁸ 

Chilling injury risks when planting field corn 

Understanding the risks associated with low soil temperatures can help you determine when to plant corn. 

In the first 24 to 36 hours after planting, corn kernels are at high risk of imbibitional chilling injury. If the temperature of the kernel's cell tissues is too low, the kernels are less pliable and more likely to rupture as they swell from the moisture absorbed during the imbibition process.   

Indicators that your corn has suffered from an imbibitional chilling injury during germination include swollen kernels that do not germinate and arrested growth of the radicle root and/or coleoptile (the corn shoot’s protective sheath). 

If your corn suffers from imbibitional chilling injury during the emergence process, this can result in failure to emerge or delayed emergence, stunting or death of the seminal root system and/or corkscrewed mesocotyl/coleoptile development caused by elasticity damage to the outer surface layers of the mesocotyl (the first true stem internode on a new corn seedling).⁹ 

Whether your newly planted corn encounters a chilling injury during germination or emergence, you can expect overall stunted plant development or even the loss of your entire stand.  

Moisture level and associated risks when planting a corn field 

Similar to soil temperature, soil moisture levels in the first 24 to 48 hours after planting corn are critical. During this time period, newly planted seeds absorb moisture needed for germination, but there is a fine line between soil being too wet or too dry.  

Adequate soil moisture for corn germination sits right around 50% of available water capacity, and uneven soil moisture at seed depth is considered the most common cause of uneven emergence.¹⁰ 

 📸: Iigora via iStock/Featuring corn field with uneven emergence.

Uneven emergence ultimately results in lower yields when nonuniform stands create an unsuitable environment for smaller, late-emerging plants that aren't able to access enough sunlight, water, and/or nutrients. While a few small plants may not seem like much of a loss, research indicates that plants that emerge on schedule aren't capable of balancing out the yield loss created by late-emerging plants.¹¹ 

If the soil is saturated with moisture at planting depth, seed rot and death may occur. If the soil is too dry at planting depth, the seed will remain dormant until adequate moisture is provided, leading to delayed germination.¹² Consistently using soil moisture testing protocols can help you gauge the risks. 

How to plant corn 

Aside from establishing timing and ensuring soil conditions are appropriate, it is essential to understand which seed depth and row width work best for your operation. 

How deep to plant corn 

Corn is generally planted at a depth of 1.5" to 2".¹³ However, it is important to base your planting depth considerations on your soil conditions. In each field, assess soil moisture at seed depth to understand the specific soil condition.  

For example, if excessive tillage, warm weather, and a lack of rainfall create drier soil conditions during the planting window, soil moisture at the standard 1.5" to 2" planting depth will likely be uneven and result in uneven germination. In this instance, you might be well advised to plant seeds deeper to avoid the uneven moisture at shallower soil depths.¹⁴ 

How far apart to plant corn  

The standard spacing recommendation for planting field corn is 30" rows.¹⁵ However, both narrow and twin-row methods have recently gained attention.  

Narrow row spacing trims each row down to 20", while twin row configurations use two rows of corn planted approximately 6" to 8" apart, alternating with the twin rows planted on 30" centers.¹⁶   

📸:@Backyard Productions via Canva/Featuring corn field with standard row spacing. 

📸:@Orest Lyzhechka via iStock/Featuring corn field with narrow row spacing. 

📸:@hxdbzxy via iStock/Featuring corn field with twin row spacing.

Both narrow row and twin row spacing methods create more biomass, but overall yields across standard, narrow, and twin spacing methods are generally similar (only varying slightly by region). Plant density is not usually affected by row width as long as you use an appropriate seed rate. 

Seeding rate 

Seeding rate is another decision that can be influenced by environmental factors as well as seed quality. To produce maximum yield, the optimal seeding rate for corn is typically around 35,000 seeds per acre, depending on the geography and other environmental conditions.¹⁷ Reducing seeding rates is usually an appealing method to save money upfront, but inclement weather and soil conditions may require a higher seeding rate (and/or replanting) to make up for greater seed and seedling mortality. Additionally, if your seed germination rates are below 90%, a higher seeding rate is also recommended.¹⁸ 

📸:@Hirurg via Canva/Featuring a corn grower inspecting his crop for pests.

Early-season corn disease, pest, and weed management 

Managing crop threats that damage corn in the early stages of growth is critical to ensure the productivity of your stand. 

Early-season corn diseases 

There are many common disease threats to Midwest corn you should scout for early in the season.  

• Leaf spot: Gray leaf spot is one of the most frequent diseases detected in U.S. corn. Overwintering in corn residue, this fungus and its spores spread to corn foliage through splashing water and wind, eventually creating enough loss of healthy leaf tissue that it interferes with photosynthesis and results in yield loss and poor grain fill. Gray leaf spot develops on cloudy, warm days with lengthy periods of dampness and high relative humidity and is most severe in corn-on-corn fields and reduced-tillage operations. Headline AMP® fungicide and Veltyma® fungicide can aid in the prevention and control of gray leaf spot.

📸:@Katja Schulz via Flickr/Featuring corn leaves showing symptoms of gray leaf spot.

• Blight in corn: Three common types of blight pose early season threats to corn. Seedling blight is a fungus that typically occurs in poorly drained, compacted, cold, and/or wet soils and can cause rot before or after germination. Seedling blight usually does not limit stands, but when seedlings are already encountering other stressors, it can impact the stand.¹⁹  

Anthracnose leaf blight is a pathogen that overwinters in corn residue or seed and is typically spread by water splashing the fungal spores onto the plant's low foliage. It thrives in mild, wet conditions and is most prevalent in corn-on-corn fields and reduced-tillage operations. As the infection increases throughout the plant and reaches a later stage in the disease process, the risk of top dieback, stalk rot, and lodging is greater. A performance-driven fungicide such as Veltyma® fungicide can provide maximum yield and consistency for your corn acres. 

📸:@International Maize and Wheat Improvement Center via Flickr/Featuring corn leaves showing damage from anthracnose leaf blight.

Another blight to watch for is northern corn leaf blight (NCLB). Like anthracnose leaf blight, NCLB overwinters and spreads to new crops by water splashing on low foliage. Corn infected with NCLB infections will have reduced green leaf area and photosynthesis, impairing grain fill and also affecting standability. Headline® AMP fungicide and Veltyma® fungicide are both labeled for use against northern corn leaf blight.  

📸:@maerzkind via Canva/Featuring corn tips showing symptoms of NCLB. 

Early-season corn pests 

Common pest threats to Midwest corn include the following: 

• Corn rootworm: The #1 pest to US corn in 2021 and 2022 was corn rootworm. Damage from corn rootworm resulted in a loss of 600 million bushels in 2021 and almost 500 million bushels in 2022. This accounts for almost half the total corn loss due to pest damage in both years. 

Both larval and adult corn rootworms are responsible for this catastrophic damage. Larvae feed on corn roots in the spring, preventing proper water and nutrient uptake. This root damage may potentially lead to lodging or infection by root rot or other diseases. Adult beetles feed on corn silks, and if the infestation is large enough, they may eat leaves as well. 

• Wireworms: One of the earliest corn pests of the season, wireworms feed underground on the seed before germination and later on the root structures of young plants, decreasing emergence rate and later killing or stunting new emerging plants.²⁰  

📸:@Katja Schulz via Flickr/Featuring wireworm.

• White grubs: Two types of white grubs threaten corn with varying severity. Annual grubs (with a one-year development period) feed in late summer and fall, causing minimal damage to established stands. Multi-year grubs have life cycles ranging from one to three years, overwintering deep in the soil and moving back to the root zone to feed the following spring. This is when most of their damage occurs.²¹ Corn seedlings whose germination and emergence are slowed by cool weather or other factors will be more susceptible to stand loss.²² 

📸:@Petra Schneider via Canva/Featuring white grub.

• Cutworms: Cutworm damage appears in the form of missing, wilted, or cut plants. Various types of cutworms, including black cutworms, can severely damage corn early in the season, as most cutting occurs within seven days of plant emergence.²³ Scouting fields early for damage is critical to understanding this threat since damage is most severe in the early stages. For example, after corn reaches V5, it’s usually too big for black cutworms to sever it.  

📸:@Frank Peairs via Canva/Featuring cutworm and cutworm damage to corn plant. 

Using a seed treatment like Poncho® 600 seed treatment can help reduce the incidence of pest damage. Additionally, Nurizma® Insecticide can be applied at the time of planting to help protect corn from soil insect pests. 

Weed management when planting field corn 

Early postemergence weed control is critical to minimizing competition for water and nutrients, which can result in yield loss. Research indicates that starting weed management at V1 growth stage can prevent yield losses greater than 5%. Beginning proactive weed management planning can help. 

Early-season corn nutrient management 

Two of the primary early-season inputs for corn include nitrogen (N) and phosphorus (P). 

Applying nitrogen fertilizers to corn is critical, as N-deficient corn can result in costly repercussions for growers. N deficiencies frequently occur as a result of inadequate fertilization and are particularly common in sandy, cold, or saturated soil conditions or if there are large quantities of low-nitrogen ​crop residue. Conducting a soil analysis to determine your average N level is key. If you discover your soil N content is too low in the spring (due to factors such as leaching from heavy rainfall), spring N applications may boost your soil health. You can apply N prior to planting or after seeds are in the ground. The ideal timing for N application will vary based on your specific location's weather conditions, soil type, temperature, and moisture level.    

Additionally, phosphorus (P) fertilizer is recommended as a starter fertilizer (applied either in-furrow or within 2" of seed during planting) for corn. This fertilization is recommended regardless of P soil level, with research indicating that P starter fertilizer may improve the young plant's nutrient uptake efficiency, potentially increasing early-season plant growth and subsequent grain yield.²⁴ 

📸:@fotografixx via Canva/Featuring a grower inspecting the season's productive yield.

How do you grow successful corn? 

There are many factors that play into how to grow successful corn. From selecting seeds and planting at the optimal time to staying ahead of disease and pest threats, it is critical to understand how to manage corn production in your specific region. By tailoring the industry's best management practices to fit your needs, growing corn can be less stressful and more fruitful for your operation in the future. 

Learn more at Grow Smart® Live: 

See how previous corn planting schedules have played out:  

• 2023 Corn Planting Pace 

Experts are available to help you make your decisions. Reach out to your seed retailer, a nearby extension office agent, or a seed company professional like your regional BASF representative. 

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Endnotes 

1. Rosser, Ben. "Agronomy Guide For Field Crops – Corn – Hybrid Selection." Field Crop News – Ontario Ministry of Agriculture, Food and Rural Affairs in Partnership with the University of Guelph, 21 Mar. 2021, fieldcropnews.com/2021/03/agronomy-guide-for-field-crops-corn-hybrid-selection/. Accessed 11 Dec. 2023. 
2. Rosser. "Agronomy Guide For Field Crops – Corn – Hybrid Selection." 
3. Geyer, Allen, and Peter Thomison. "Delayed Planting Effects on Corn Yield: A “Historical” Perspective." Agronomic Crops Network, https://agcrops.osu.edu/newsletter/corn-newsletter/2019-12/delayed-planting-effects-corn-yield-%E2%80%9Chistorical%E2%80%9D-perspective. Accessed 11 Dec. 2023. 
4. Elmore, Roger. "Best Corn Planting Dates for Iowa." Integrated Crop Management, crops.extension.iastate.edu/cropnews/2012/03/best-corn-planting-dates-iowa. Accessed 18 Dec. 2023. 
5. Nielsen, R. L. "The Planting Date Conundrum for Corn (Purdue University)." Corny News Network, Apr. 2022, www.agry.purdue.edu/ext/corn/news/timeless/pltdatecornyld.html. Accessed 10 Dec. 2023. 
6. Bernards, Mark. "Delayed Corn Planting — Costs and Considerations." CropWatch, 10 Mar. 2016, cropwatch.unl.edu/delayed-corn-planting-%E2%80%94-costs-and-considerations. Accessed 11 Dec. 2023. 
7. Nielsen, R. L. "Early-Planted Corn & Cold Weather (Purdue University)." Corny News Network, 3 May 2023, www.agry.purdue.edu/ext/corn/news/timeless/EarlyPlantedCornColdWthr. Accessed 11 Dec. 2023. 
8. Nielsen, R. L. "Soil Temperatures & Corn Emergence (Purdue University)." Corny News Network, 12 Apr. 2021, www.agry.purdue.edu/ext/corn/news/articles_21/SoilTempEmergence-0412.html. Accessed 10 Dec. 2023.  
9. Nielsen, R. L. "Emergence Problems in Corn (Purdue University)." Corny News Network, May 2022, www.agry.purdue.edu/ext/corn/news/timeless/EmergenceFailure.html#:~:text=in%20unusual%20directions.-,Cold%20Soils%3A,-Cold%20soils%20and. Accessed 13 Dec. 2023. 
10. Nielsen, R. L. "Requirements for Uniform Germination and Emergence of Corn (Purdue University)." Corny News Network, Apr. 2020, www.agry.purdue.edu/ext/corn/news/timeless/germemergreq.html. Accessed 13 Dec. 2023. 
11. Abendroth, Lori, and Roger Elmore. "What's the Yield Effect of Uneven Corn Heights?" Integrated Crop Management, crops.extension.iastate.edu/encyclopedia/whats-yield-effect-uneven-corn-heights. Accessed 13 Dec. 2023. 
12. Nielsen, R. L. "Soil Moisture & Corn Seed Depth (Purdue University)." Corny News Network, Apr. 2021, www.agry.purdue.edu/ext/corn/news/timeless/SoilMoistSeedDepth.html. Accessed 13 Dec. 2023. 
13. Quinn, Dan. "How Deep Should Corn Be Planted?" Pest&Crop Newsletter, 13 Dec. 2022, extension.entm.purdue.edu/newsletters/pestandcrop/article/how-deep-should-corn-be-planted/. Accessed 13 Dec. 2023. 
14. Nielsen. "Soil Moisture & Corn Seed Depth”. 
15. Licht, Mark. "Row Spacing for Corn." Integrated Crop Management, crops.extension.iastate.edu/encyclopedia/row-spacing-corn-0. Accessed 13 Dec. 2023. 
16. Battel, Bob. "Planting Corn in Twin Rows." MSU Extension, 5 Jan. 2018, www.canr.msu.edu/news/planting_corn_in_twin_rows. 
17. Licht, Mark and Clemens, Zachary. "Considerations for Corn Seeding Rates." Integrated Crop Management, 9 Apr. 2021, crops.extension.iastate.edu/blog/mark-licht-zachary-clemens/considerations-corn-seeding-rates. Accessed 13 Dec. 2023. 
18. Licht and Clemens. "Considerations for Corn Seeding Rates."  
19. "Seedling Blights in Corn." Integrated Pest Management Programs, ipm.ca.uky.edu/content/seedling-blights-corn. Accessed 13 Dec. 2023. 
20. Wright, Bob. "Early Corn Insect Scouting." CropWatch, 22 July 2019, cropwatch.unl.edu/early-corn-insect-scouting. Accessed 13 Dec. 2023. 
21. "White Grubs." OSU Extension - Oklahoma State University, 17 Aug. 2022, extension.okstate.edu/programs/turfgrass-science/educational-materials/white-grubs.html. Accessed 18 Dec. 2023. 
22. "White Grubs." Extension at the University of Minnesota, 2021, extension.umn.edu/corn-pest-management/white-grubs#factors-that-increase-losses-1193311. Accessed 18 Dec. 2023. 
23. Wright, Bob, and Keith Jarvey. "Early Corn Insect Scouting." CropWatch, 22 July 2019, cropwatch.unl.edu/early-corn-insect-scouting. Accessed 13 Dec. 2023. 
24. Endres, Greg. "Update on Carrington REC Corn Fertilizer Research: Phosphorus and Zinc." NDSU Agriculture, 6 Apr. 2023, www.ndsu.edu/agriculture/ag-hub/impact-stories/update-carrington-rec-corn-fertilizer-research-phosphorus-and-zinc. Accessed 22 Jan. 2024. 

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